Process and apparatus for reconditioning mineral oils



c. J. @mmm `En" An..

PROCESS AND APPARATUS FOR HEGONDITIONING MINERAL OILS Filed Nov. ll,1925 INVENTOR d .an

MENGE nl'. ltlllDM, 0F WXLKINSBUJR, .MND Mill RECHT, Uh lPJENNSWLVId.

LPMUJES MD @MPPMTWUS FUR RIHEUUMJDITJEONWG milled..

Application led November l1, 1925 Serial No. 66,300.

'llhe present invention relates to the treatment of mineral oils, andparticularly to the reconditioning of .oils which, for example, havebeen taken from electrical equipment, such as transformers, circuitbreakers, 'and the like, but the invention is also applicable to thetreatment of other used or impure mineral oils. l v

According to the present invention, it is proposed to subject the impureor used oil to a process of'puritication under such conditions as tosubstantially retard oxidation of the oil during treatment and insuchmanner as to remove Water, dissolved gases and volatilizableimpurities, and to then remove other impurities such as unsaturates,resinous compounds, acidic compounds, oxidation products, carbon,sludge, sediment, etc.

According to the present invention, it is proposed also to heat the oil,to a limited extent, under conditions which will prevent overheatingthereof and to utilize heat which would otherwise he wasted forpreheating the oil prior to its introduction intol the reconditioningapparatus.

'llhe nature and objects of the invention may be readily understood byreference to the accompanying drawings which show more or lessdiagrammatically a preferred embodiment of our invention, but it will beunder.- stood that we do not conne ourselves to the use of theparticular apparatus shown or to the specific manner of practicing theinvention, as various changes in construction and modes of operation arecontemplated within the spirit of our invention.

lin the drawings the figure is a schematic view of the entire apparatus.

ln the drawings, 2 designates an oil supply pipe through which impure orused mineral oils to be reconditioned are introduced into the apparatus.The oilto be treated may, for instance, be an oil which has been used ina transformer or in a circuit breaker or other electrical equipment. @ilmay be supplied to pipe 2 from any suitable source through any preferredmethod of feed, either by gravity or otherwise.

Pipe 2 leads through the top 3 of a tank l y having a bottom 5 andhaving a cylindrical inner wall 6 spaced inside thereof, and having aperforate extension '7 at its lower end. This might, for example, beformed of fine mesh screen. Pipe 2 within the tank t terminates lute,and the temperature is @lill ber of the heater where it rises in thinhlms over the surface of the heating units, which units are in closeproximity to each other. llt is preferred that the partitions or heatersare at such distance as to permit a maximum heat absorption withoutoverheating any part ofthe oil, thereby minimizing oxidation ordecomposition resulting from heating. llt will be understood, however,that the oil may be heated and the stream of oil broken up in the vacuumchamber to release easily volatile substances, Irases and water, inother ways.

Leading from the upper part of the tank 4l is a pipe 13 which preferablyleads into a heat exchanger 14 arranged about the pipe 2. lin the lowerpart of the heat exchanger 14 is a drain pipe 15 through whichcondensates may be removed. Leading from the heat exchanger 14C is apipe 16 that connects with a suitable vacuum pump designated 1'? anddriven by a motor 18. The pump 17 maintains the pressure in the tank lat a suitably reduced pressure for the edectual separation. and removalof water, gases, volatiles, etc.. at the desired temperature. the

pressure being preferably maintained at substantially 2.5 pounds persquare inch absopreferably maintained at about 150 Fahrenheit.

Suspended from the walls 6 within the tank d and below the heater 9 area plurality of deflectors 19 which are preferably of the alternatelyreversed cone type. During the operation of the apparatus, oil, whichpasses through the heater 9, froths over the top thereof and falls ontothe first of the deflectors 19. v

llt Hows successively from one deflector to another in thin films, sothat any gases which remain in the oil can be readily released. From thelowermost dedector A19kthe oil falls into the bottom of the tank whereit colle.

ttt

litt@ lilith Leading from the bottom of the tank 4 is a pipe 2Oconnecting with a suitable pump, preferably a centrifugal or otherrotary type of pulnp, 21. The pump 21 may also bc driven by motor 18.Leading from the outlet side of the pump 21 is a pipe 22 that connectswith the receiving end of a reaction tank 23. The reaction tank 23 ispreferably vertically disposed. and has a. conical bottom 24 which maybe drained by a sludge cock 25. It may have a removable cover 9.6, andnear the top thereof is an outlet pipe 27. Pipe .22 preferablydischarges close to the conical bottom of the tank whereby agitation andthorough mixing of an adsorptive compound or substance is secured. Atthe same time, the tank has sufficient volume so that the flow of oiltherethrough is very gradual and quiet in the upper part thereof. Thisprovides for an initial turbulent introduction of the oil with asubsequent quiescent period of reaction. The outlet pipe 27 preferablyconnects with a manifold 28.

Leading from the manifold 28 are branch. pipes Q9 connecting withdfilters 30. Each pipe 29 preferably has a valve 31 therein, so that theflow of oil from the manifold to any filter may be controlled at will.

Filters 30 preferably include an outer casing 32, a base 33 and an innerporous shell 84, the inner shell 34 being spaced from the outer shell32. Pipes 29 lead to the space 35 between the inner porous shell and theouter casing'. Leading from the central chamber 36 within the porousshell 34 of each filter is a pipe 37. Each of the pipes 37 has a valve-38 therein and these pipes connect with a manifold 39. From manifold 39the oil is preferablyT conducted through a heat exchanger 40 alsolocated about the pipe 2. From the heat exchanger 40 the o-il may beconducted through pipe 41 to a suitable collecting or storage reservoir.v

While we have described one form of filter, we are not necessarilyconfined to the particular form shown, as any device for this purposewhich may be found suitable, may be substituted. wWe do prefer, however,that the filter plate, such as the shell 34, be of a baked porousmaterial whose porosity may be determined by the character of thematerial used. Vith such a material there can be no danger ofcontamination of the oil with particles of lint, suspended or solublefilter material, or other substance, as might result with the use ofother types of filters.

As the oil is withdrawn from the bottom of tank 4 through pipe 20, it isdesirable to in t'roduce a` compound into the oil. For this .purpose wehave shown a container 43 having 2a proportional feeder 44 of anypreferred type at thebottom thereof, this feeder being suitably driven,preferably by a drive connection, such as belt 45 from the motor 18.With such l an arrangement the speed of the feed device may be inaccordance with the speed of the pump 21. The proportional feederintroduces dry partially evacuated adsorptive material down a pipe 46into the pipe 20. A deflector 46 is preferably provided in pipe 2()adjacent the terminal of pipe 46 so as to agitate the oil in the pipe 20at this point to canse it to more readily mix and carry away the dryadsorptive compound or substance.

The air-tight container 43 may have a pipe at 47 terminating within thetank at 48 so that the contents of the 'container 43 will be subjectedto the same partial vacuum maintained in the tank 48. This prevents anyappreciable amount of air from being introduced into the o il throughthe proportional feeding device, and tends to remove any contained gasesor air from the adsorbent material.

In the practice of the invention, the partially warmed or preheated oilenters the heatmg means for the initial stage of its puriication. It isWell known that if the oil is overheated, especially in the presence ofoxygen, undesirable decomposition will result. During the practice ofthe present invention, any such undesirable results are eliminated.

The incoming oil, in passing through the heater, is maintained in astate of agitation, a turbulent motion being imparted thereto by theheating of oil by the parallel heaters under the maintenance ofconditions of partial vacuum in the tank 4. This agitation is increasedby the combined ebullition, dcgasification and vaporization of containedimpurities. The effective heating of the oil is thus effected withoutchemical reactions of a destruct-ive or harmful nature.

Under the conditions in which the oil is heated, moisture mechanicallyheld or dissolved in the oil, dissolved gases, such as air, oxygen,nitrogen, light hydro-carbon gases and volatiles, are continuouslyeliminated from the oil. These vapors and gases are continuously removedby the vacuum pump 17, so that the oil is thoroughly evacuated at thisstage of the process. Some of these vapors condense in the heatexchanger 14 from which they may be removed.

The purpose of the perfor-ate screen 7 is to reduce, to a minimum, theloss of finely divided or atomized oil, this screen serving to obstructthe passage of such oil particles to the vacuum pump.

The deflectors 19 are of such a length and number as to eect a thoroughdehydration and degasification, and volatilization of undesirableconstituents before the oil finally drains into the bottom of the tankAs the evacuated or dehydrated oil from which the undesirable volatileshave been removed passes out the pipe 20, a dryy adsorptive compound orsubstance is supplied thereto from the container 43 as-previouslydescribed, and is also evacuated as hereinbefore explained by thewithdrawal of conlltl aaaaaai tained gases therelt'rom throu h the pipedi'. hn evacuated adsorbent is t us introduced into an evacuated oil..This dry material is a desiccated adsorptive compound or substancehaving a high capacity or adinity tor impurities contained in the oil.This compound or substance may consist oi an activated or preparedcharcoal, a iilter clay, silica gel, or a suitable combination ot theseor similar substances in suitable proportions.. We preter to use anearth substance such as bentonite,

or a char, particularly a char especially intitl tltl

tended tor hlter ot' the tvvo.

This desiccated adsorptive substancev is thoroughly mined into the oilhy the action oi the centrifugal pump 2i., As the oil dovvs through thereact-ion chamber 23, the desiccated substance vvill combine vvith theimpurities, These impurities are recognized as unsatnrates, resinouscompounds, acidic compounds, omdat-ion products, etc. its previouslysuggested the oil is thoroughly agitated in the bottom et the reactionchamber, vvhile it later passes through a aone ot quiescent reaction,The time ot reaction is suhicient to hilly enable the desiccatedadsorptive substance to combine 1a'ith impurities. The reaction is morerapid due to the evacuation ot gases trom the adsorbent prior to itsintroduction into the oil Both condensed moisture and gases are removed:trom the cell spaces, and the total area oi the surtaces are 'therebyavailable tor the reactions vvhich ensue. The adsorbent reactions areboth more rapid and complete due to the greater athnity oit such treatedadsorbent vvith oil which has been hrst heated in a vacuum..

purposes, or a combination The oil derving trom the reaction tanlr thenpasses through the hlters. The hlters serve to remove the tinely dividedsuspended particles ot desiccated adsorptive substance, together vvithsuch impurities as they have collected, vvhile the reconditioned oilflows through the tilters and into the pipe 39. lltrom pipe 39 the oil,vvhich is still heated, llovvs through the heat exchanger l@ to turtherheatthe used or impure oil passing 'through pipe 2 and then thereconditioned oil may he conveyed through pipe ll to any suitablecollecting vessel.

.ds the oil containing the linely divided desiccated adsorptivesubstance passes through the tlter, the particles ct earthy material inthe oil collect on the tilter plate 3l and produce a mat which serves toedectively remove hnely divided particles in the oil. lin

other vvords the desiccated adsorptive sub stance also aids the emciencyot the lilter.

With the arrangement ot filter shown, one

or more tilters can be idle by the closing ot the hill valves leadingthereto, while the other iilters remain active.. This permits ot thecleaning or repair oit one or more tilters vvhile the other hlters arein operation, adapting the process removing Water and contained gasestrom the to a continuous method et operation. @briously, hovvever, vveare not conlined to any particular arrangement or ty e ot hltersm Ttvvill he apparent that t e, operation is carried out under conditionsvvhich reclude im onidation ot the oil as air is eaclu ed until the oilhas heen completely reconditioned and cooled By reason oi the adsorptivematerial having heen evacuated prior to its introduction into the oil,it has a greater athnit-y 'it :tor the im urities in the oil. Because otthe tact that t e oilhas heen evacuated and the vvater and the lightvolatiles removed theretrom, the evacuated adsorptive material vvillhave a greater attnity 'tor the impurities remaining in the oil, auch asresinous compunds, unsatnrates, etc., andthe adsorptive is not spent inremoving vvater or light hydrocarbone. Therefore, less adsorptivematerial need be used and the time tor reaction is reduced to theminimum.. This permits the Siae ot the apparatus to be reduced and makesit particularly adaptable lor small installa, tions.

The term 66desiccated 4adsorptive suhstance99 as herein used denotes anyvvell linovvn -or suitable iinely-divided desiccated substance orcompound that may be intro duced into the oil and which has an adsorptive athnity -lor the recognized impurities in the oil, but which is notdissolved thereby. The term dehydrated as used in the presentspecihcation and claims vvith reference to the oil, means anhydrous, asdo the terms dry and desiccated, as used in connection with theadsorptive compounds.

lille claim as our invention:

l. it method ot reconditioning electric insulating mineral oil vvhichcomprises first evacuating the oil, lthen introducing an "5 evacuatedadsorbent into the oil and While maintaining the oil out ot contact withatmosdll `pheric gases and then tiltering the oil to remove theadsorbent While lmaintaining it out of contact with atmospheric gases.

2., all method ot treating mineral oil used tor electrical insulationpurposes which comprises evacuating the oil, introducing into the oilafter `it has been evacuated an anhydrous adsorbent Which has also beenpartially evacuated and While maintaining the oil out oit" contact `Withatmospheric gases and Water, and then filtering the oil vto remove theadsorbent, the oil being filtered substantially out oit contact Withatmospheric gases.

8. A method of treating electrical insulating mineral oil which consistsin introducing partially evacuated adsorbent into an evacuated oil andthen filtering the oil, the process being effected out ot contact vvithwater and atmospheric gases.

l.' A method of reconditioning electric in sulating mineral oil, vvhichconsists in hrst Hill ldd

oil, then introducing an evacuated adsorptive wm l ing the oil to removet e spent adsorptive material, the oil being kept free of contact withatmospheric gases and moisture during the process.

5. A method of reconditioning .electric inl sulating mineral oil, whichcomprises heating the oil while under a partial vacuum and out ofcontact' with atmospheric gases, whereby dissolved moisture, gases andlow boiling impurities are driven ofi from the oil, 1ntrol5 ducing adesiccated adsorbent into the oil So treated and while maintaining theoil out of Contact with atmospheric gases, and then filtering the oil toremove the adsorbent while maintaining it, out of contact With atmoseOpheric gases.

6. A method of reconditioning oils used for electrical insulatingpurposes, which consists in rendering the oil anhydrous and free ofgases by heating it in a partial vacuum,

then adding a dry adsorptive substance having an affinity forunsaturates, resinous constituents, acidic compounds and oxidationproducts, and then filtering the oil, the process being effected underconditions which preclude oxidation of the oil or prevent moisture fromcoming into contact therewith.

7. A method of reconditioning electrical insulating oil, which consistsin dehydrating the oil by heating the same at sub-atmospheric pressurein a confined chamber which precludes oxidation of the oil or theabsorption of atmospheric moisture, then mixing a dry adsorptivecompound therewith and allowing the same to combine with impurities inthe oil, and then filtering the oil, these steps also being effectedWhile maintaining the oil free of Contact with atmospheric gases.

8. A method of reconditioning electrical insulating oil, which consistsin heating divided streams of oil in a partial vacuum, fiowing theheated oil over a defiector plate while under a partial vacuum,collecting the oil so treated, then introducing an evacuated adsorptivesubstance into the oil, and thereafter filtering the oil, the oil beingexcluded from contact'with air and water during the process.

9. A method of reconditioning electrical insulating oil, which consistsin heating the `oil in a chamber from which air is excluded,

fiowing the heated oil over defiectors within the chamber, withdrawingvapors and gases from the chamber, removing the heated oil from thechamber, mixing an evacuated adsorbent substance therewith, andfiltering the o0 oil, the oil being confined against exposure toatmospheric gases and moisture during the entire recess.

10. method of reconditioning electrical insulating oil, which consistsin introducing the oil into a heater within a chamber from which air isexcluded, heating the oil in the I heater, flowing the hot oil over adeflector in said chamber, withdrawing gases and vapors from saidchamber, circulating such gases and vapors about the incomin supply ofoil to thereby preheat the oil be ore it passes into the heater,withdrawing the heated oil from the bottom of the chamber, mixing adesiccated adsorptive with the oil, filtering the oil, and passing thefiltered oil through a heut exchanger associated with the incoming oilsupply, whereby the treated oil also serves to partially preheat theuntreated oil entering the heater, the oil being confined againstexposure to atmospheric gases during the entire recess.

. 11. pparatus for reconditioning electrical insulating oil, including atank, means for withdrawing gases from the tank, a heater within thetank, an oil supply for delivering oil to the heater, defiectors in thetank below the heater for receiving the oil therefrom, means forwithdrawing oil from the bottom of the tank, enclosed means forintroducing an evacuated adsorbent substance into .the oil upon itsremoval from said tank, and enclosed means for filtering the oil.

l2. Apparatus for reconditioning electrical insulating oil includingmeans for dehydrating and degasifying the oil and removing volatilizableimpurities therefrom, means for supplying a desiccated adsorptivesubstance to the oil after it flows from the first named means, andmeans for filtering the oil to which the desiccated adsorbent substancehas been supplied, the apparatus being closed against exposure of theoil to the atmosphere.

13. Apparatus for reconditioning electrical insulating oil, includingmeans for heating, degasifying and dehydrating the oil, a reaction tank,means for `removing dehydrated oil from the first named means into thereaction tank, means for introducing an evacuated adsorbent materialinto the oil before it flows into the' reaction tank and after it leavesthe first named means, and filtering means connected with the reactionchamber, said apparatus being substantially air-tight to prevent the oilbeing treated from coming into contact with air. A

In testimony whereof we have hereunto set our hands.

CLARENCE J. RODMAN. MAX HECHT.

